Background
Robert Mathew Marshall fatally stabbed Adam Cordingley three times with a hunting knife at Marshall’s Bungonia property on 23 March 2024. Cordingley had discovered that Marshall had had an affair with Cordingley’s partner and, unbeknownst to Marshall, an opportunity for a confrontation was arranged on the night. Marshall found Cordingley at the property, armed himself with a knife after seeing an unfamiliar car, and asked Cordingley to leave.
After an angry discussion about the affair, Marshall turned away. Cordingley then punched him and tore his shirt. Marshall reacted by deliberately stabbing Cordingley three times; two deep wounds, including one that severed an artery, caused his death. Marshall called emergency services immediately. A jury acquitted him of murder but convicted him of manslaughter, finding that he had acted in excessive self-defence.
The Court’s Holding
McGuire J sentenced Marshall to six years’ imprisonment, with a non-parole period of three years and eight months. The sentence was backdated to 27 April 2026, making Marshall eligible for parole on 26 December 2029.
The Court found that Marshall did not intend to kill or cause grievous bodily harm, but had committed an unlawful and dangerous act by stabbing an unarmed man three times with a large sharpened knife. Although Cordingley was the initial aggressor and the attack was unplanned, Marshall’s response significantly exceeded what was reasonable in the circumstances as he perceived them.
Marshall’s ADHD, anxiety disorders and trauma-related disorder materially contributed to heightened fear, emotionality and impulsivity, reducing moral culpability only minimally. His prior good character, remorse, treatment engagement, low reoffending risk and good rehabilitation prospects were mitigating factors, but full-time custody was required for punishment, accountability, denunciation and recognition of the harm caused.
Key Takeaways
- An excessive-self-defence manslaughter conviction does not preclude a substantial custodial sentence.
- The deceased’s initial assault and the spontaneous nature of the confrontation mitigated, but did not justify, three knife wounds inflicted on an unarmed person.
- Mental health conditions reduced Marshall’s culpability only modestly because their effect on the deliberate stabbing was limited.
Why It Matters
The decision illustrates the sentencing balance in excessive-self-defence cases: a genuine defensive context can reduce culpability, yet lethal escalation using a weapon may still require full-time imprisonment. The Court distinguished a police taser case in which a community correction order had been imposed, stressing the materially greater seriousness of repeatedly stabbing an unarmed civilian with a hunting knife.